1. Field of the Invention
The present invention relates to a method of sharing a data transceiver, a data transceiver antenna, sensing receiver, and a sensing antenna.
2. Description of the Related Art
A cognitive radio (CR) system may recognize that a primary user does not use a frequency band that is already allocated to the primary user and may use the frequency band. To prevent interference to the primary user, the CR system may recognize an appearance when the primary user appears in the band being used by the CR, and may yield the band to the primary user. Sensing whether the primary user uses a channel being used by the CR system may be referred to as an in-band sensing.
In the case that the primary user appears in the channel being used by the CR system, the CR system may continuously perform a spectrum sensing with respect to a candidate channel so that the CR system may switch from the channel being used when the primary user appears in the channel. Sensing candidate channels that may be used as substitutions, in the case that the primary user uses the channel being used, may be referred to as an out-band sensing.
The in-band sensing is a process where the CR system determines whether the primary user appears in the channel being used, and the in-band sensing may be performed when a channel that the CR system desires to be used is sensed by the CR system. When a data transmission and reception and a spectrum sensing are simultaneously performed during the in-band sensing, an interference signal due to the data transmission and reception may affect the spectrum sensing, and thus, the simultaneous performing of the data transmission and reception and the spectrum sensing may be impossible. Accordingly, a transmission quiet period (QP) that stops the data transmission and reception may be exist, during the data transmission and reception, to perform the in-band sensing, and the in-band sensing may be performed during the transmission QP.
The out-band sensing is a process where the CR system prepares candidate channels to immediately substitute for the channel being used when the primary user appears in the channel being used. The out-band may not be currently used by the CR system. When a CR device includes a separate sensing receiver and a sensing antenna the data transmission and reception may be performed using the data transceiver and the data transceiver antenna in an in-band, and simultaneously the out-band sensing may be performed using the sensing receiver and the sensing antenna in an out-band. The data transmission and reception may not pause for performing the out-band sensing in the CR system, and thus the CR system has an advantage of performing the out-band sensing without affecting a quality of service (QoS). Because of the above advantage followed by including the separate sensing receiver and the sensing antenna, the CR system is considered to include the receiver and the sensing antenna in addition to the data transceiver and the data transceiver antenna, and a number of prototypes have developed to have the same format as the above CR system
When the spectrum sensing is performed, the in-band sensing and the out-band sensing are not always performed. The in-band sensing may be performed based on a predetermined ‘quiet period’ and the out-band sensing may also be performed based on a predetermined schedule. The data transmission and reception may depend on a system. In a case of a time division multiple access (TDMA) system, the data transmission and reception may not be continuously performed, and the data transmission and reception may be performed in a predetermined period of time based on a predetermined schedule and may not be performed at other times. When the data transceiver, the data transceiver antenna, the sensing receiver, and the sensing antenna are used for only their own purposes, the data transceiver and the data transceiver antenna, the sensing receiver, and the sensing antenna may be inefficiently utilized.
FIG. 1 illustrates a conventional wireless communication system 100 including a data transceiver 150, a data transceiver antenna 140, a sensing receiver 120, and a sensing antenna 110.
Referring to FIG. 1, the sensing receiver 120 may be connected to the sensing antenna 110 to receive sensing data for a spectrum sensing, and may transmit the received sensing data to a sensing signal processing unit 130 performing a spectrum sensing calculation. In this instance, the data transceiver 150 may be connected to both the data transceiver antenna 140 and a data signal processing 160 processing transmitted or received data, to perform a data transmission and reception.
FIG. 2 illustrates, based on time, an operation of a data transceiver and a sensing receiver in the conventional wireless communication system of FIG. 1.
Referring to FIG. 2, the data transceiver 150 and the data transceiver antenna 140 may be used for a data transmission and reception, and may perform the data transmission and reception when data to be transmitted or to be received based on a predetermined transmission and reception schedule exist in the wireless communication system 100. When data to be transmitted or to be received does not exist, such as ‘A’, the data transmission and reception may not be performed and the data transceiver 150 and the data transceiver antenna 140 may remain in a standby mode. During a transmission QP, the data transmission and reception may not be performed and the data transceiver 150 and the data transceiver antenna 140 may remain in the standby mode to synchronize with the spectrum sensing and to smoothly perform an in-band sensing for a channel being used.
The sensing receiver 120 and the sensing antenna 110 may be used for receiving data for a spectrum sensing, and may perform an in-band sensing or an out-band sensing based on a predetermined sensing schedule. The in-band sensing may synchronize with the data transmission and reception and may receive data from an in-band channel during a transmission QP. The out-band sensing may be performed in a different channel from a channel for the data transmission and reception, and thus may be performed based on a predetermined sensing schedule regardless of the data transmission and reception. The sensing process may have a period of a standby mode, such as ‘B’, where the sensing data is not received.